This invention relates to photographic slide projectors, and more particularly to means for straightening the picture slides in the compartments of the magazine adjacent to the compartment from which a slide is to be removed for projection, or to which it is to be returned after projection.
The compartments of slide magazines are frequently made sufficiently thick so that they can receive slides in plastic mounts, or slides mounted between glass plates. However, when such magazines are used with slides mounted in the usual cardboard mounts, which are much thinner than plastic mounts or glass mounted slides, then difficulties are encountered. The thinner cardboard mount has so much play in the compartment that it may tilt far enough to bring the upper portion of the slide in one compartment in overlying relation to the next adjacent compartment. If a slide in a compartment next to the one from which a slide is to be removed or returned, tilts far enough to lean over the space of the compartment out of which or into which a slide is to be moved, the overhanging slide from the next compartment may interfere with the proper operation of the slide transfer member attempting to remove a slide, and may block the insertion of a slide attempted to be replaced in its proper compartment. This blocking of the return of a slide is particularly serious, since the slide transfer mechanism moves relatively rapidly, and if the slide attempted to be returned butts against an overhanging part of a slide from the next adjacent compartment, both slides are likely to be damaged or destroyed, and there is the further possibility of serious damage to the slide transfer mechanism.
This excessive and dangerous tilting of a thin slide in a thick compartment of the magazine occurs particularly with magazines of the type having a slot in the bottom of the magazine, and a fixed ramp which engages the bottom edges of the slides as the magazine moves, raising the slides as they successively reach the location at which they are to be withdrawn for projection. Such magazines usually have one side wall which is relatively low, and the ramp lifts the slide up high enough so that the bottom edge of the slide is at or above the elevation of the top edge of the low wall of the magazine, so that the slide may be moved horizontally from the magazine to the film gate or projection gate of the projector. When the slide is not engaged with the elevating ramp, it is sufficiently low so that the partitions between successive compartments will maintain the slides against excessive tilting. But when the slide is raised by the ramp to a higher elevation, a much larger part of the height of the slide is above the top edge of the partition, and hence the slide can tilt to a great extent, if the slide is relatively thin, such as a cardboard mounted slide, and if the compartment receiving the slide is relatively thick, such as a compartment adapted to receive plastic mounted or glass mounted slides.
The present invention overcomes the difficulty caused by tilting of the thin slides in the thick compartments, by providing, on the projector, resilient flexible elements such as brushes, which engage the edges of the successive slides as the magazine moves, and which shift the slides to an upright position tight against one of the upright partition walls which form the compartments. This shifting of the tilted slides to an upright position occurs as the slides arrive at a position where excessive tilting would be harmful. Other slides, at a distance from the compartment from or to which a slide is being moved, are free to tilt, since tilting of these other slides is not harmful.